Functional Group Modulation in Carbon Quantum Dots for Accelerating Photocatalytic CO₂ Reduction

Abstract

This study investigates the mechanism behind the enhanced photocatalytic performance of carbon quantum dot (CQD)-induced photocatalysts. Red luminescent CQDs (R-CQDs) were synthesized using a microwave ultrafast synthesis strategy, exhibiting similar optical and structural properties but varying in surface functional group sites. Model photocatalysts were synthesized by combining R-CQDs with graphitic carbon nitride (CN) using a facile coupling technique, and the effects of different functionalized R-CQDs on CO2 reduction were investigated. This coupling technique narrowed the band gap of R1-CQDs/CN, made the conduction band potentials more negative, and made photogenerated electrons and holes less likely to recombine. These improvements greatly enhanced the deoxygenation ability of the photoinduced carriers, increased light absorption of solar energy, and raised the carrier concentration, resulting in excellent stability and remarkable CO production. R1-CQDs/CN demonstrated the highest photocatalytic activity, with CO production up to 77 μmol g–1 within 4 h, which is approximately 5.26 times higher than that of pure CN. Our results suggest that the superior photocatalytic performance of R1-CQDs/CN arises from its strong internal electric field and high Lewis acidity and alkalinity, attributed to the abundant pyrrolic-N and oxygen-containing surface groups, respectively. These findings offer a promising strategy for producing efficient and sustainable CQD-based photocatalysts to address global energy and environmental problems.

Bright solid-state luminescence and high-temperature resistance of Ga-doped carbon dots with ultra-wideband white emission for light-emitting diodes

“…The absorption peaks located at 3223 cm −1 , 1770 cm −1 , 1463 cm −1 , 1198 cm −1 , and 455 cm −1 were assigned to –OH, CO, –CH 2 , B–O and Ga–O, groups, respectively, and are in agreement with the aforementioned XPS results. 43–49 The absorption peak of CO bonds at 1770 cm −1 is assigned to the vibration of CO bonds in –COOR functional groups. The absorption peak of the –OH group at 3223 cm −1 originates from adsorbed water.…”

“…The absorption peaks of CO bonds at 1700–1725 cm −1 and the absorption peaks of –OH groups at 900 cm −1 of the –COOH functional groups are not observed. 48,49…”

A graphitic carbon nitride photocatalyst with a benzene-ring-modified isotype heterojunction for visible-light-driven hydrogen production

“…Heterojunction composites therefore minimize the rate of charge carrier recombination, maximize visible light utilization, and viably enhance the photocatalytic efficiency of g-C 3 N 4 . [47][48][49] Notably, constructing isotype heterojunctions of g-C 3 N 4 with distinct band structures within its two dissimilar crystal phases is effective in facilitating the separation of photogenerated charge carriers. For instance, Sundaram et al created isotype heterojunctions of g-C 3 N 4 through a one-step thermal treatment of melamine-urea, melamine-thiourea, and ureathiourea mixtures to achieve superior, stable visible-lightinduced photocatalytic degradation of methylene blue dye.…”

Surface‐Chemistry‐Mediated Near‐Infrared Light‐Direct‐Driven Photocatalysis toward Solar Energy Conversion: Classification and Application in Energy, Environmental, and Biological Fields

“…[1][2][3] Since photocatalytic H 2 O splitting reaction on TiO 2 electrode was first discovered by Fujishima and Honda in 1972, [4] pursuing artificial solar energy utilization serving mankind is the goal we always strive for refs. [5][6][7][8][9][10]. The utilization of solar energy for the generation of chemical fuels, environmental purification, H 2 generation, N 2 fixation, and disease treatment through artificial photocatalysis and photothermal catalysis has been considered as a promising solution to address the energy, environmental issues, and oncotherapy, due to the outstanding advantages in low-cost, nontoxicity, and stability.…”